You infringe our IP! No, you infringe ours!

Japan's Matsushita and South Korean combine LG Electronics have both issued lawsuits against each other after both companies accused the other of patent infringement.

Matsushita was first. It claims LG's plasma display panels use technology it owns governing the way heat can be dispersed from the screens. It asked the Tokyo District Court to ban LG from importing the allegedly offending displays into Japan and from selling those units already there.

LG then countersued Matsushita's Panasonic subsidiary in South Korea, this time alleging a similar PDP-related patent violation. It has asked South Korean trade authorities to block the importation and sale of Panasonic PSP products. The company is also considering filing a similar lawsuit in Tokyo.

If Matsushita prevails in Japan, LG said, it would be forced to complain to the World Trade Organisation (WTO).

"Matsushita's actions are designed to keep a curb on the expanding PDP industry in Korea," the company alleges, according to a report in South Korea's Joong Ang Daily.

The legal battle follows the collapse of negotiations between the two companies. Talks began in August, but neither was able to reach an agreement with the other.

The spat arises from increasing friction between Japanese and South Korean PDP makers as the latter have aggressively challenged their rivals' dominance of the market.

Fujitsu and Samsung were involved in a similar tussle in April this year, though the two settled their differences out of court with a cross-licensing agreement in June. ®